Hi Capt. Le Velle,
You might try LEKKO I.T.E.S. at http://www.lekko.org (http://www.lekko.org)
They are located in Maasdam, but are an international society with an eye on the tugboat industry.
They might be able to put you in touch with a broker, or a private party.
You might find their bi-monthly magazine “LEKKO International†of interest.
Regards,
Marty